Sirolimus (formerly known as rapamycin) is a drug commonly used after renal transplants to prevent organ rejection. In this study, pemphigus subjects with active disease will begin taking sirolimus in conjunction with corticosteroids, using a similar regimen used for organ transplantation to treat pemphigus. While increasing sirolimus and decreasing the corticosteroids, subjects will be monitored over a 12 month period to evaluate their disease response. The purpose of this study is to observe data trends.